I have a Solstice GXP, 2.0L LNF. I'm dyno tuned. I've been chasing a nasty vibration at 1k rpm. Well...after ripping into the motor and not finding anything...I decided to data log. I haven't data logged since before the vibration started about a year ago. Don't worry, I've put about 500 miles on it since the vibration started! After data logging and comparing I noticed some stuff. My commanded AFR used to be 14.7. Now it's 13.79 all the time, unless I'm in DFCO (gas shut off coast down in gear basically). Before it would command 29.4 and get it, now it's commanding 27.58 and getting it. My car has 82k on it....I haven't touched the tune in over 3 years. But, let me give some background. In the spring of '18, I made the mistake of taking it to Belle Tire for a leaky rim...and I had something come up on the way over, so I left it with them. Solstice's have very specific lifting instructions, which must be followed or you will crush the flooring. When I returned, they insisted that I look at all the lift points....odd I thought. When I made it home, I noticed I heard some pinging. Well, upon further inspection they ran the exhaust into a hoist arm...so I had to replace from the cat down to the mesh hinge ( I have Solo Street Race, so no mufflers). I'm not certain if the vibration was there before or after this. I just know they drove my car for 5 miles for a leaky tire....and of course with the tune, I have no rev limiter. My car still pulls hard, still breaks the tires loose in 2nd and 3rd, still gets 23psi of boost.....its just this vibration and commanded AFR that I can't figure out. I'm thinking either the wide-band O2, the downstream O2, MAF or MAPs....any suggestions or help???? I appreciate it. You guys helped me figure out my HPFP was bad 3 years ago and it was almost easier then changing a tire to replace!! I appreciate any help/advice.

 

Do you have someone that can look at the tune? I wouldn't think the ECU would adjust it's commanded AFR on it's own but not real familiar with stock ECU function. I wanted to ask why you don't have a rev limiter? You should be able to set the rev limiter where ever you want with the tune but that's very risky to remove it completely.

 

I shouldn't say I don't have a redline, it was supposedly moved to 7k rpm, but I've never hit it. My last tune was at 6500rpm when the car was much newer. I don't have anyone that can look at the tune, let alone anyone to pull it for me. I'm thinking the wide-band O2 sensor has decided it doesn't want to work anymore. I'm just tired of throwing parts at this car in hopes of fixing things. I spent almost $1k on my hpfp issue before I finally threw in the towel and replaced it. I don't want to replace both O2 sensors and the MAF only to find out it's something else. And to be honest, I've had nothing but issues with this car since I bought it 7 years ago. It wasn't tuned right by the previous guy...and he put a Fujita CAI on it, which in itself, on a Solstice/Sky creates all kinds of weird tuning issues because the MAF is in a weird location. But, I know that my car has commanded 14.7 AFR for the past 4 years since my dyno tune, now suddenly it's commanding 13.79...and almost looks like it's locked at 13.79 or 27.58.....There's no in between. Fuel trims look good, it's just this commanded and the extremely rich issue....I came here again seeking advice because not too many guys over on the Kappa (Solstice/Sky platform) have the mileage on their cars like I do...and not many are as heavily modded. Most have a CAI and exhaust and Trifecta/GMPP tune and that's it. Many have just gotten to the waterpump issue stage of 40-60k miles. So that's why I'm here...hoping someone here is a tuner/tech that can point me in a direction or help me with checking my wideband o2 and regular o2 sensors..... I do have the Torque app for data logging a little bit....

 

Anyone got ANY ideas? I'm begging!!! LOL!! Just really irritating because I want to drive my car and I'm done throwing parts at it like I did when I had my HPFP issue.... If I don't get help, I'm gonna throw both O2 and a MAF sensor at it...

EDIT: Anyone live in SE MI that has HPTuners that would be willing to look at my tune?

 

I'd say your tune is messed up. Could your o2 sensors also be messed up, yes. Your car shouldn't be stuck in a certain afr and that's in the tune. Your fuel cutoff afr also isn't correct either. Why not take it to pwerks up in Chicago or seek them out online as they specialize in your car? That's my recommendation.

 

Appreciate the help. Not going to Pwerks. Had an issue with them early on in my adventures and it cost me some money. I would literally drive to North Carolina first to DDMWorks before I ever dealt with them. Instead, car is going to dealership, having it fixed and then selling it. I'm at the end of my rope with this problem and it's been another straw on the camel's back.

My final question....how can a tune. that's been in the ECM for over 4 years, suddenly get messed up? My car was dyno tuned by ZZP 4 years ago.

 

The tune doesnt just mess up unless the ecu is bad but thats a rare case.

Im not sure on the vibration issue but you may want to check your motor mounts as well as your transmission mount. If your car is 2007.5+ you may have a broken torque arm that connects the rear diff to the trans.

For the engine stuff check codes if you can and report back. Can you only look at commanded afr woth torque or can you see actual afr as well? Is actual following commanded?

 

Thanks...finally someone answered. I have no codes...not even a pending code. My actual does follow commanded. I did find something interesting and that's my actual ambient barometric pressure. It's off by the same amount. Not certain on the Solstice where outside pressure is measured, or if this is even something of concern. My main concern is a bad vibration at 1k rpm. It gets super rich around there at usually a 11.5. I have torque logs and can post if you can read them...I really appreciate the help!!

 

I wonder if you have a sensor reading far enough off that your car is commanding Power Enrichment when it shouldn't be. Someone that knows all the factors that dictate PE should know if this is possible or not.

 

Yeah I have limited LNF knowledge. We need Ecaulk in here.

 

Op can you describe the vibration more? Is this at idle? Or when youre taking off?

 

I think The vibration has come about since the CAFR has decreased. It is a motor vibration and happens in neutral or driving at about 1k rpm. It's so bad when the car is cold that the plastic squeaks hurt my ears!! Coincidentally, since I've been logging, my measured AFR at that point jumps to 18.5 then the next capture it's all the way down at 11.8 and hovers around that till the rpm increases/decreases. This is where the vibration is the worst. Don't get me wrong...car still runs like a scalded cat. I've had it to 6k with no issue...no studder. Heck, it still lays rubber at the top end of 2nd and 3rd at full boost (22psi).

 

How old are the plugs and what gap are you running?

Getting the lnf to idle well is a bitch. So I understand it correct, the vibration started after the tire replacement and driving?

Another thing to check is for coked valves and verify a lifter hasnt fallen due to an over rev (usually happens when you slap the rev limiter, but it could happen from other things).

If you can find someone with hptuners to get a log file that would help a lot.

 

Plugs were changed this spring and gapped to spec. No mount problems either...

Well...I cant say for sure when the vibration started. But it was right around that time. They hit one of their hoist arms and broke the mesh portion of the exhaust loose. When I picked up the car, it had 6 miles more on it (I'm like Cameron's dad..."he knows the mileage Ferris"), so I know they drove it. Where and how? No clue. Furthermore they didnt tell me about the incident...i found it about a day later. I just remember complaining about it a day or so later. Midas did check out the entire exhaust to make sure when they installed the new front piece that everything was tight. I never thought then to start looking at my torque app stuff. I

I do have one question. Can the downstream O2 sensor cause the car to run rich if it's super lazy? Sometimes it goes 10 to 15 seconds after the upstream shows rich before the downstream will show rich... But it doesnt change the CAFR.

I've been trying to find someone near me to do a data log on hptuners...but the guys that have it near me, won't do it. Hell...if I had it that's all if be doing!! Lol

 

Post-cat 02 sensor doesn't affect fueling. Only functions to let ECU know if cat is working adequately or not.

 

If it doesnt think the cat is working properly...would it make it run rich IF the O2 sensor is showing a very lean condition?



Let me give a bit of background on my car and issues I've had. At around 55k the WP (waterpump) went...very common on the Kappa platform (Solstice/Sky/Opel), especially the turbo cars. When they replaced my WP they accidentally cut my cat with the torch, so they replaced it. My car had a tune in it when I bought and it was awful. Couldn't boost past 5psi if the coolant temp gauge read less then 170 degrees. So, I added IC piping. The Fujita CAI was on the car when I bought it.... (very hard to tune a correct MAF reading with the Fujita on a Kappa because the MAF is in the wrong place). The car also had Solo Street Race Exhaust (no mufflers) when I bought it. 4 years ago when the car had 58k on it, I had it dyno tuned at ZZP. I asked that he please not give me an aggressive tune and to move the redline to 7k. Well...in the end he gave me a very aggressive tune. My car runs on 93 octane and 93 only!! If it gets anything less...it burbles and sputters and almost backfires. The engine runs very rough when this happens. Car ran like a top though....always at CAFR of 14.7 consistently. The next summer as I was driving one day with the A/C on, while coasting and in gear, it started backfiring. hmmmm.... Got a code several days later of p2188, too rich at idle. Added a bottle of Techron and it seemed to fix the issue for a while. Long story short, that whole summer I played around with the p2188 and trying to figure out the issue. Nobody could point me toward a solution. Until one day I heard the irregular rhythm of the HPFP. That's when I replaced it. I did 2 consecutive oil changes on it to get the extra gas out of the cylinders. (To date it's not had 4 additional oil changes in 10k). Once everything was back I logged to make sure that the car ran good. At that point it was running just a slight touch lean, but would go rich at WOT. So I was worried about it. Spring of '18 I replaced the thermo (this is a huge pain in the **** on a Kappa!!). Shortly there after I took the car to have a slow leak in a rear tire fixed. I had to leave it at the tire shop because I had errands to run that day (a regret I still have!!). With Kappas, there are very specific lifting instructions...and mine has LEDs on the undercarriage as well, so they had to follow these lifting instructions, which I supplied them and told them. When I returned to pick up my car 4 hours later, the tech and writer asked me to "check out my car" and make sure it was good. Something I thought odd as they both stood and watched me. I merely looked at the lifting points and the floor to make sure it wasn't crushed...nothing else. As I drove off I distinctly remember feeling a strange new vibration in the drivetrian....but was more worried about a pinging noise and the 6 miles that were now on my car that weren't on it when I left it. When I got home, I quickly realized that the mesh hinge on the exhaust was failing and that the clamps were off of it and "pinging" as the motor was running. Still thinking nothing of the vibration, I ordered a new portion of exhaust from Solo and had it installed at a Midas where the guys were all car guys and very "sharp". Upon inspection of the old portion of exhaust, we noticed that it had run into something solid...hmmmm....a lift arm perhaps at the tire shop 3 days prior??? They proceeded to make sure that all of the exhaust was secure and not leaking anywhere. As I was returning home, I could really feel the vibration. I thought at that point it was the new exhaust. So the car has pretty much sat since last August because of this vibration. And I really didn't think about torque logging until about the past 2 months. So I only have he logs from 2 years ago and then the last 2 months in Torque...

Some days this vibration is ear shattering...some days it's slight. My first thought on the vibration was a skipped link in the balancer chain.... But now since I've been logging I'm almost positive that the CAFR of 13.79 has something to do with it. It's just running way to rich and I have no clue what could cause this. I'm hoping someone will see my pleas on the other 3 kappa forums that has hptuners and lives in SE MI and will help me out....

Is there a way to post an excel file here so that someone can look at it from Torque????

 

It can on the LNF, the ecu will tweek CAFR to test the 2nd o2 sensor.

See if you can find a load transition that causes it, I'd also be leaning towards coked valved at this point. With the mileage I would be surprit they arent.

 

Good to know. What does it do to test the cat?

 

I know that my downstream seems (on torque app) to stay lean for a good 10+ seconds after the upstream goes normal to rich. So that's why I was wondering if it could cause the ECM to command my lower AFR of 13.79.

 

As long as it's not commanding that ARF for awhile (>2mins) I would be to worried. I would check your intake runners for build up, that can cause the vibration almost like a misfire but not registered as a misfire.

As far as I can tell it's just testing the cat performance as an emissions check. It goes rich and lean to varying degrees for a short time to see the there is a difference between the two. Which is why you should drive an LNF for 20-30miles after writing a new tune if you want to get cruise and idle tuned well.

 

So here's a scenario with the upstream O2 (USO2) and downstream O2 (DSO2)

USO2 - 1.1-1.2 for 1 second
DSO2 - 0.1 for 10 seconds

then a trigger happens, like I go 35-40% throttle...the USO2 will go rich (mayb 0.7) and then finally the DSO2 will show rich again of 0.7 or so. The DSO2 seems to be no more then a "switch" in my logs. Something extreme needs to turn it rich or lean....which I thought was a bit odd.

Not sure if anyone can read my torque log, but I attached it....it's in excel I believe.

 

Here's my log from 2016...when my car was running great!

 

Not true. Downstream will effect fuel and fuel trims. BOTH o2 sensors are monitored carefully from the ecu. My downstream was lazy and my fuel mileage was terrible and cold start it would spit, if it's too lazy it will trick the computer into leaning or richening the fuel too much. May or may not throw a code

 

I do remember that issue with my Camaro back in 1999... I had a lazy O2 sensor that never set a CEL but I had horrible gas mileage and a nasty vibration at idle. I did attach my logs from Torque a few posts ago if anyone can look at them and tell me what you think....I was going to order a downstream O2 sensor today and replace it just to see what happens. I did notice that the protective cover on the wires on mine is moved up the harness. So I have an inch or so of wires showing right at the base of the sensor. The Solstice has a "L" style pipe that comes down off the cat. My sensor sits right in the bend on the inside, between the firewall and pipe and almost directly behind the cat....

 

If you can get me a log on your car I'll take a look at it. Most likely your fuel trims are skewed causing the AFR issue or if you are on a blow through MAF setup there is a vac leak somewhere. With the blow through setups its harder to detect a vac leak because the car will still run fairly normal.

My best guess though would be the MAF, Ive seen them get dirty and start to read off just a lil, but not enough to toss a code.